In the search for hydrocarbons and in the evaluation of coal - and synfuel-type deposits, drilling represents an expensive commitment. A drilled hole can become worthless unless basic logs taken in such a hole can provide information vital to evaluating the potential of the surrounding area. If the lithology of the area is simple and known, analysis of the logs will give good values of the parameters needed to evaluate a reservoir and to determine reserves. However, the complex composition of mixed lithologies being encountered worldwide in oil and gas exploration and production having greatly complicated log analysis. Also, current log analysis methods are not adequate in many areas. There is, therefore, a need for logs to specifically and quantitatively identify basic rock types (limestone, dolomite, sandstone, and mixtures of these), clay type and volume, and minerals that adversely affect the logs used to estimate reserves.